Energy-saving anti-free flow portable pump for use with standard PVC IV tubing

ABSTRACT

The present invention comprises an apparatus for pumping fluid through tubing. The apparatus includes a tubing base having a tubing support surface and a stop platen. The stop platen and the tubing support surface each comprise respective ridges aligned with a direction of fluid flow through the apparatus. The respective ridges are operatively arranged to engage a wall of tubing along a longitudinal axis of the tubing. In some aspects, the respective ridges are arcuate in a plane orthogonal to the direction of flow. In some aspects, the respective ridges are centered with respect to a transverse axis of the tubing and have a respective width less than an outside diameter of the tubing.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation-in-part patent application under 35 USC 120, which claims the benefit of U.S. patent application Ser. No. 10/117,515, filed Apr. 5, 2002, entitled, “ENERGY-SAVING ANTI-FREE FLOW PORTABLE PUMP FOR USE WITH STANDARD PVC IV TUBING” and incorporated by reference herein.

FIELD OF THE INVENTION

This invention relates to a pump for providing fluid for injection into a patient. More specifically it relates to a method and apparatus for an ambulatory infusion pump for pumping liquid through standard intravenous (IV) tubing.

BACKGROUND OF THE INVENTION

Infusion pumps for delivering fluid to a patient are well known in the art. Two general categories of infusion pumps known in the art are ambulatory pumps and large volume parenteral (LVP) pumps. These pumps deliver fluid to a patient through tubing at higher accuracies than gravity drip tubing delivery systems.

LVP pumps are relatively large infusion pumps that can provide a fluid to a patient for 4-6 hours or more on a single battery charge, or indefinitely from an AC power connection. They may operate on standard IV polyvinyl chloride (PVC) tubing. Most available LVP pumps completely collapse the PVC tubing during operation to ensure that there is no free flow to the patient or back flow to the fluid reservoir. This leads to very high power consumption when using standard tubing. Thus, a battery capable of powering the pump for 24 hours is very heavy and bulky. A patient receiving fluid from an LVP pump must stay within reach of a power cord, or push a wheeled stand with the LVP pump and battery mounted on it. In addition, fully collapsing the tubing deforms the tubing. The tubing cross section becomes more elliptical the longer the pump operates on it. Less fluid is discharged from the tubing as the cross section becomes more elliptical, leading to negative flow rate errors. The pump rate accuracy decays proportional to the amount of time an individual tubing set is used to deliver fluid to a patient. An example of an LVP infusion pump is shown in U.S. Pat. No. 4,653,987 (Tsuji et al.).

Ambulatory pumps are smaller infusion pumps that can be attached to a patient's belt, allowing them to move around without a bulky LVP pump. However, there are several drawbacks in comparison to the LVP pump. To reduce the weight to a level where a patient can carry the pump, the size of the battery is reduced considerably. The reduced battery cannot provide the power required to completely collapse standard PVC tubing. Instead, many ambulatory pumps require the use of special dedicated IV sets, or special silicon tubing threaded through a cassette to be inserted into the pump. This specialized equipment increases the cost of using the pumps. Even with special dedicated IV sets or silicon tubing and cassettes, many ambulatory pumps can only provide fluid to a patient for a few hours on a single battery charge. An example of an infusion pump that requires a dedicated IV set is shown in U.S. Pat. No. 5,772,409 (Johnson). An example of an ambulatory infusion pump that requires silicon tubing and cassettes is shown in U.S. Pat. No. 5,791,880 (Wilson).

Another problem with the infusion pumps currently in the art is the danger of free flow of fluid when the tubing is inserted or removed from the pump. An occluder is used to completely collapse the tubing while the tubing is outside the pump. The occluder is disengaged when the tubing is installed in the pump. The tubing is occluded again before the tubing is taken out of the pump. However, there is no means currently in the art to ensure that the tubing is occluded before the tubing is installed into or removed from the pump. Thus, the tubing may accidentally become unoccluded while the tubing is outside the pump, allowing fluid to flow freely to the patient. This overdose of fluid may be harmful or even lethal.

Clearly, then, there is a longfelt need for an ambulatory infusion pump that utilizes standard PVC tubing, operates for approximately 24 hours on one battery charge, and can prevent free flow of fluid into the patient.

SUMMARY OF THE INVENTION

The present invention comprises an apparatus for pumping fluid through tubing. The apparatus includes a tubing base having a tubing support surface and a stop platen. The stop platen and the tubing support surface each comprise respective ridges aligned with a direction of fluid flow through the apparatus. The respective ridges are operatively arranged to engage a wall of tubing along a longitudinal axis of the tubing. In some aspects, the respective ridges are arcuate in a plane orthogonal to the direction of flow. In some aspects, the respective ridges are centered with respect to a transverse axis of the tubing and have a respective width less than an outside diameter of the tubing.

The stop platen is arranged to be moved to a position closest to the tubing base and when the stop platen is in this position, the tubing is formed in first and second lobes. The lobes form passages through said first tubing. In some aspects, the lobes are symmetrical with respect to the longitudinal axis.

The present invention also includes a method for pumping fluid through tubing.

A general object of the present invention is to provide an ambulatory pump that utilizes standard PVC tubing.

Another object of the present invention is to provide an ambulatory pump with high accuracy, preferably better than ±5% accuracy.

It is a further object to provide an ambulatory pump that can deliver fluid to a patient at a relatively high volume flow rate, for example 125 ml/hour, for at least 24 hours.

It is yet another object to provide an ambulatory pump that prevents the free flow of fluid into the patient when the tubing is installed and removed.

These and other objects, features and advantages of the present invention will become readily apparent to those having ordinary skill in the art upon a reading of the following detailed description of the invention in view of the drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The nature and mode of operation of the present invention will now be more fully described in the following detailed description of the invention taken with the accompanying drawing figures, in which:

FIG. 1 is a side view of a first embodiment of the present invention, with the platens arranged to allow fluid flow from a reservoir;

FIG. 1 a is a perspective view of an occlusion platen;

FIG. 1 b is a perspective view of a pump platen with a stop platen thereon;

FIG. 2 is a side view of a first embodiment of the present invention, with the platens arranged to allow fluid flow to a patient;

FIG. 3 is a side view of a first embodiment of the present invention, with the platens arranged to pump fluid to a patient;

FIG. 4 is a side view of a first embodiment of the present invention, with the platens arranged at the end of a pump cycle;

FIG. 4 a is a cross sectional view of the tubing and the pump platen showing the dimensions of the stop platen and the tubing;

FIG. 4 b is a cross sectional view of the tubing and the pump platen, with the stop platen completely collapsing a portion of the width of the tubing;

FIG. 5 is a perspective view of an embodiment of the present invention;

FIG. 6 is an exploded view of an embodiment of the present invention;

FIG. 7 is an electrical schematic of the motor drive circuit of an embodiment of the present invention;

FIG. 8 is a front perspective view of an embodiment of the present invention, a section of tubing, and an occluder, with the door of the present invention closed, and the tubing unoccluded;

FIG. 9 is a front perspective view of an embodiment of the present invention, a section of tubing, and an occluder, with the door of the present invention closed, and the occluder being inserted in the keyhole of the present invention;

FIG. 10 is a front perspective view of an embodiment of the present invention, a section of tubing, and an occluder, with the door of the present invention open;

FIG. 11 is a front perspective view of an embodiment of the present invention, a section of tubing, and an occluder, with the door of the present invention open, and the tubing installed in the pump;

FIG. 12 is a front perspective view of an embodiment of the present invention, a section of tubing, and an occluder, with the door of the present invention closed, and the tubing installed in the pump;

FIG. 13 is a front perspective view of an embodiment of the present arranged to pump fluid through the tubing;

FIG. 14 is a front perspective view of an embodiment of the present invention, a section of tubing, and an occluder, with the door of the present invention opened, and the tubing installed in the pump;

FIG. 15 is a front perspective view of an embodiment of the present invention, a section of tubing, and an occluder, with the door of the present invention open, and the tubing uninstalled from the pump;

FIG. 16 is a front perspective view of an embodiment of the present invention, a section of tubing, and an occluder, with the door of the present invention closed, and the tubing occluded;

FIG. 17 is a perspective view of a device of the present invention;

FIG. 18 is an exploded view of the device shown in FIG. 17;

FIG. 19 is a front perspective view of an occlusion platen shown in FIG. 18;

FIGS. 20 and 21 are side views of a tube support plate and a pump platen; and,

FIGS. 22-28 are side views of the device showing a sequence of operation.

DETAILED DESCRIPTION

It should be appreciated that, in the detailed description of the invention which follows, like reference numbers on different drawing views are intended to identify identical structural elements of the invention in the respective views.

A first embodiment of the present invention is shown in FIG. 1 and generally designated 10. Apparatus 10 is an infusion pump comprising pump base 20 with tubing base 31 fixed thereto. Tubing 21 is routed over tubing base 31 underneath occlusion platens 22 and 29, and pump platen 25. Occlusion platen 22 is fixed to platen support 55. Occlusion platen 29 is fixed to platen support 55. Pump platen 25 comprises stop platen 26, and is fixed to platen support 55. Motor 42 is fixed to pump base 20. Motor 42 drives camshaft 38. Camshaft 38 is supported by shaft supports 40 and 41. Cams 35, 36, and 39 are all fixedly mounted on camshaft 38. As camshaft 38 rotates when driven by motor 42, cams 35, 36, and 39 are rotated at the same rate. Cam 35 is operatively arranged to cyclically drive occlusion platen 29 between a first, unoccluding position and a second, occluding position. The first position is shown in FIG. 1, wherein occlusion platen 29 is not in contact with tubing 21. As cam 35 is rotated by shaft 38, platen support 55 is driven down by cam 35. This drives occlusion platen 29 towards tubing 21. Occlusion platen 29 is driven to a second position, shown in FIGS. 2, 3, and 4, where occlusion platen 29 occludes tubing 21. As the shaft continues to rotate, cam 35 moves away from platen support 55. Spring 52, shown on FIGS. 5 and 6, provides upward force on platen support 55 to lift occlusion platen 29 back to the first, unoccluded position. Cam 39 drives occlusion platen 22 through a similar cycle. Occlusion platen 22 is driven from a first, unoccluded position to a second, occluded position. However, occlusion platen 22 occludes tubing 21 at substantially different times than occlusion platen 29. Occlusion platen 22 is shown occluding tubing 21 in FIGS. 1 and 4. Spring 52, shown on FIGS. 5 and 6, provides upward force on platen support 55 to lift occlusion platen 22 back to the first, unoccluded position when cam 39 moves away from platen support 55 due to the rotation of shaft 38.

Cam 36 drives pump platen 25 from a first position to a second position as shaft 38 rotates. The first position is shown in FIGS. 1, 2, and 4 a. The pump platen is not in contact with tubing 21. As shown in FIG. 4 a, width d of stop platen 26 is less than width w of tubing 21. As shaft 38 rotates, cam 36 drives platen support 55 to a second position, shown in FIGS. 3, 4, and 4 b. In the second position, pump platen 25 depresses tubing 21. Stop platen 26 completely collapses a section of the width of tubing 21, as shown in FIG. 4 b. Stop platen 26 prevents pump platen 25 from occluding tubing 21. Stop platen 26 does not occlude tubing 21 because stop platen 26 is narrower than tubing 21, as shown in FIG. 4 a. Occlusion by the pump platen is undesirable because it would require significantly more power than partially occluding the tubing, as shown in FIGS. 3, 4, and 4 b. Further, the tubing does not deform as readily when partially deflected by the pump platen, as compared to the deformation caused by occluding the tubing.

In one embodiment, the platens are spring loaded, to allow the platens to be overdriven. This ensures tubing 21 is occluded by the occlusion platens or partially occluded by the stop platen, regardless of the dimension of tubing 21. This improves the accuracy of the pump when using tubing of varying dimensions. Otherwise expensive, complicated measurement devices are needed to ensure that the tubing is deflected the appropriate amount by each platen. Springs 52, shown in FIGS. 5 and 6, accomplish this spring loading.

As shown in FIGS. 1-4, 1 b, 4 a, and 4 b, an embodiment of stop platen 26 is a platen that extends the length of the pump platen, and is centered along the width of the pump platen. However, it should be readily apparent to one skilled in the art that many other configurations of stop platens could be used and these modifications are intended to be within the spirit and scope of the invention as claimed. For example, the stop platen could extend only a portion of the length of the pump platen, or it could be located away from the center of the pump platen. A stop platen shorter than the pump platen could be off center along either the length or width of the pump platen, or both.

FIG. 1 shows platen 22 occluding tubing 21, and platens 25 and 29 above tubing 21. This is the first position in the pump cycle, which allows fluid from a reservoir (not shown) in flow communication with end 14 of tubing 21 to flow into the tubing proximate the pump platen. FIG. 2 shows platen 29 occluding tubing 21, and platens 22 and 25 above tubing 21. This position allows fluid to flow to a patient (not shown) in flow communication with end 12 of tubing 21. FIG. 3 shows platen 29 occluding tubing 21, platen 25 depressing tubing 21 until stop platen 26 completely collapses the central portion of the width of tubing 21, and platen 22 above tubing 21. This configuration forces the fluid in tubing 21 towards end 12 of the tubing. FIG. 4 shows platens 22 and 29 occluding tubing 21, and platen 25 depressing tubing 21 until stop platen 26 completely collapses the central portion of the width of tubing 21. This is the end of the cycle. Platens 25 and 29 move up again to return to the first configuration of the pump cycle shown in FIG. 1.

FIGS. 1-6 show a single pump platen 25. However, it should be readily apparent to one skilled in the art that a plurality of pump platens may be used, and these configurations are intended to be within the spirit and scope of the invention as claimed.

FIG. 1 a is a perspective view of occlusion platen 29. FIG. 1 b is a perspective view of pump platen 25 with stop platen 26 thereon.

FIG. 5 is a perspective view of an embodiment of the present invention, designated 50. FIGS. 1-4 show motor 42 mounted in line with camshaft 38 so that the platens are visible. To reduce the volume of the pumping assembly, an embodiment locates the motor parallel to the camshaft, coupling them with gears 45 as shown in FIGS. 5 and 6. It should be readily apparent to one skilled in the art that many mechanical configurations are possible, and these modifications are within the spirit and scope of the invention as claimed.

FIG. 6 is an exploded view of an embodiment of the present invention in perspective. Springs 52 provide an upward force on the platen supports to return them to an upper position when each cam moves away from the platen supports. Springs 52 are connected between the platen supports and the pump base 20. Springs 51 spring load the platens so that they may be overdriven. This enables the pump to be used with tubes of differing dimensions, as discussed above.

In an embodiment, pump assembly 50 is mounted in cabinet 70, as shown in FIGS. 8-16. Cabinet 70 comprises keyhole 73, case 74, display 75, keypad 76, and door 78. Also shown in FIG. 8 is tubing 21 with an occluder 80. Occluder 80 has a first end 81, a second end 82, and a slit 83. To occlude tubing 21, tubing 21 is routed through slit 83 proximate first end 81. Slit 83 is narrowest where the slit is closest to end 81. Slit 83 is wider proximate second end 82. Fluid flows freely through tubing 21 when the tubing is located proximate second end 82. Thus, tubing 21 is shown unoccluded in FIG. 8. Fluid may flow freely through the tubing to a patient.

Free flow of fluid through the tubing is prevented with the present apparatus as follows. FIG. 9 shows occluder 80 being inserted into slot 73 of the present invention. Second end 82 must be inserted to open door 78, as first end 81 is too thick to fit into keyhole 73. As occluder 80 is inserted into keyhole 73, tubing 21 is forced towards first end 81, as shown in FIG. 10. Thus to open door 79, tubing 21 must be occluded by occluder 80. Door 78 unlocks as shown in FIG. 10, exposing the pump assembly. Door 78 is unlocked when hooks 72 disengage loops 71. Tubing 21 is routed along tubing channel 79, between the tubing base and the platens, as shown in FIG. 11. Door 78 is closed, as shown in FIG. 12. Occluder 80 is removed from keyhole 73, and tubing 21 is moved through slot 83 until it is unoccluded. This is shown in FIG. 13. The pump may now operate to deliver fluid to a patient.

To remove the tubing from cabinet 70, occluder 80 is again inserted in keyhole 73. This forces tubing 21 to first end 81, occluding the tubing. Door 78 opens, as shown in FIG. 14. The tubing is removed from the pump in FIG. 15. FIG. 16 shows the tubing outside the pump and pump door 78 closed. Tubing 21 is still occluded. In the above-described manner, the present invention requires the tubing to be occluded before the door can be opened. This will prevent medical personnel from forgetting to occlude the tubing before it is removed from the pump.

FIG. 17 is a perspective view of a device 100 of the present invention.

FIG. 18 is an exploded view of device 100 shown in FIG. 17. Pump platens 102 and 104 swivel about axis 106 due to the action of cams 108 and 110, respectively, and springs 112. Cams 108 and 110 are shaped so that as the cams rotate, the cams oscillate across the surfaces 114 and 116, respectively. For example, the contact point for cam 108 moves back and fourth between lines 118 and 120 on pump platen 102. In like manner, occlusion platens 130 and 132 swivel about axis 106 due to the action of cams 134 and 136, respectively, and springs 112.

Although two pump platens are shown in FIG. 18, it should be understood that the present invention is not limited to any particular number of pump platens. For example, a single pump platen or more than two pump platens can be used in device 100. In general, increasing the number of pump platens reduces and smoothes out the peak torque associated with occluding the tubing (shown in FIGS. 22-26) with the pump platens, as described below. With a reduction in peak torque, a less rugged gear train 138 is needed and less power may be needed to drive the pump platens. However, if too many pump platens are used, the complexity of device 100 is disadvantageously increased.

FIG. 19 is a front perspective view of occlusion platen 130 shown in FIG. 18. It should be understood that the description for platen 130 also is applicable to occlusion platen 132. Apex 140 of protrusion 142 is formed to minimize the stress placed upon tubing (not shown) used in embodiment 100. Specifically, apex 140 is formed with a particular curvature or radius. As a result, the tubing responds to the alternating compressions in a more consistent manner, over a longer period of time, increasing the accuracy of embodiment 100. In general, apex 140 is configured so that the deformed tubing is formed in a shape with a minimal inside energy. As a result, the tubing has the smallest inside stress and plastic deformation. Reducing inside stress and plastic deformation decreases the flow rate error, which is typically measured after 96 hours.

In some aspects, platen 130 includes insert 143, which slides into the main body of platen 130. The use of insert 143 allows the main body of 130 and the insert to be made of different materials. For example, a plastic may have desirable characteristics with respect to the interaction of the platen with the cams, but may lack the structural strength needed for the protrusion. Likewise, a metal may have the strength characteristics desired for the protrusion but may lack the characteristics desirable for interaction with the cams. Thus, the main body can be made of the plastic and the insert can be made of the metal.

FIGS. 20 and 21 are side views of the tube support plate 150 and pump platen 102. The following should be viewed in light of FIGS. 20 and 21. Tube support plate 150 is not shown in FIG. 17. It should be understood that the description of pump platen 102 also is applicable to pump platen 104. Pump platen 102 includes a stop platen 152. In general, stop platen 152 is the portion of pump platen 102 that pushes against tubing 154 to occlude the tubing as shown in FIG. 21. In general, stop platen 152 is formed by platen surface 156 and includes ridge/protrusion 158. Ridge 158 is convex with respect the main body 160 of platen 102. In some aspects, ridge 158 is arcuate, specifically in a plane orthogonal to the direction of fluid flow through apparatus 100 (shown in FIGS. 22-26 below). That is, the ridge is arcuate as shown in the front view of FIGS. 20 and 21. In some aspects, the ridge is centered with respect to the tubing along the axis 162. The ridge has a width measured orthogonally with respect to the direction of fluid flow (in and out of the page as shown in FIGS. 20 and 21). This orientation is along axis 162 in FIG. 21. In some aspects, the width is less than a diameter (not shown) of the tubing. It should be understood that when references are made with respect to an alignment regarding tubing 154, such reference assumes that the tubing is secured within platen 102.

Platen 102 includes a concavity 164. In some aspects, stop platen 152 is disposed within concavity 164. That is, platen 152 forms a part of concavity 164. In some aspects, concavity 164 is parallel to a longitudinal axis 166 (shown in end view) for tubing 154. In general, axis 166 is parallel to the direction of fluid flow in device 100. Concavity 164 holds tubing 154. In some aspects, concavity 164 is shaped so that tubing 154 does not shift in a direction substantially parallel to axis 162.

In some aspects, support plate 150 includes ridge/protrusion 168. In general, ridge 168 is the portion of plate 150 which engages tubing 154 and towards which stop platen 152 pushes to occlude the tubing as shown in FIG. 21. In some aspects, plate 150 is continuous with respect to the stop platen engaging the plate. Ridge 168 is convex with respect the main body 170 of plate 150. In some aspects, ridge 168 is arcuate, specifically in a plane orthogonal to the direction of fluid flow through apparatus 100 (shown in FIGS. 22-26 below). That is, the ridge is arcuate as shown in the front view of FIGS. 20 and 21. In some aspects, the ridge is centered with respect to the tubing along the axis 162. The ridge has a width measured orthogonally with respect to the direction of fluid flow (in and out of the page as shown in FIGS. 20 and 21). This orientation is along axis 162 in FIG. 21. In some aspects, the width is less than a diameter (not shown) of the tubing. In some aspects, ridges 158 and 168 are symmetrical with respect to axis 172, orthogonal to axis 162.

Concavity 164 includes surfaces 174 and 176. Stop platen 152 is located between surfaces 174 and 176. In some aspects, surfaces 156, 174, and 176 form a continuous surface within concavity 164. In some aspects, surfaces 174 and 176 are symmetrical with respect to longitudinal axis 166 and axis 172. In some aspects, stop platen 152 is symmetrical with respect to axis 172. In some aspects at least a portion of surfaces 174 and 176 are arranged to engage tubing 154 when the tubing is pressed between platen 102 and plate 150. Stop platen 152 and ridge 168 are configured so that when the tubing is engaged by platen 152 and ridge 168, for example, as shown in FIG. 21, the deformed tubing is formed in a shape with a minimal inside energy. As a result, the tubing has the smallest inside stress and plastic deformation. Reducing inside stress and plastic deformation decreases the flow rate error, which is typically measured after 96 hours.

Tubing 154 includes an inner surface 178. Device 100 is arranged to compress tubing 154 between stop platen 152 and ridge 168 by moving pump platen 102 from the position shown in FIG. 20 to the position shown in FIG. 21. In FIG. 21, stop platen 152 is in a closest position to ridge 168. In FIG. 21, sections of surface 178 are brought into contact. As a result, tubing 154 is formed into lobes 180 and 182. Lobes 180 and 182 form passages through which liquid can pass. In some aspects, and as shown in FIG. 21, the sections of surface 178 are diametrically opposed with respect to longitudinal axis 166. In some aspects, ridges 158 and 168 are arcuate and symmetrical with respect to axis 162. Also surfaces 174 and 176 can be formed so that tubing 154 engages these surfaces and lobes 180 and 182 are substantially symmetrical with respect to axis 162 and 166. In these aspects, a top half 184 of the circumference of tubing 154 is engaged with concavity 164 as shown in FIG. 21.

FIGS. 22-28 are side views of device 100 showing a sequence of operation. FIGS. 22 through 28 show the operation of occlusion valves 130 and 132 and pump platens 102 and 104. Direction of fluid flow 190 also is shown in FIGS. 22-28. After FIG. 28, the sequence begins again with FIG. 22. FIGS. 22-28 also illustrate the use of two pump platens in a sequenced fashion. It should be understood that device 100 can operate in a “reverse” fashion (not shown), such that the direction of flow is from right to left in FIGS. 22 through 28.

Thus, it is seen that the objects of the present invention are efficiently obtained, although modifications and changes to the invention should be readily apparent to those having ordinary skill in the art, and these modifications are intended to be within the spirit and scope of the invention as claimed. 

1. An apparatus for pumping fluid through tubing comprising: a tubing base having a tubing support surface; and, a stop platen, said stop platen comprising a first ridge aligned with a direction of fluid flow through said apparatus.
 2. The apparatus recited in claim 1 wherein said first ridge is arcuate in a first plane orthogonal to said direction of flow.
 3. The apparatus recited in claim 1 further comprising a first tubing with a wall, said first tubing comprising a first longitudinal axis aligned with said direction of flow; and, wherein said first ridge is operatively arranged to engage said wall of said first tubing along said first longitudinal axis.
 4. The apparatus recited in claim 3 wherein said first tubing comprises a first outside diameter, said first ridge comprises a first width, and said first width is less than said first outside diameter.
 5. The apparatus recited in claim 3 wherein said tubing support surface further comprises a second ridge aligned with said direction of fluid flow.
 6. The apparatus recited in claim 5 wherein said second ridge is operatively arranged to engage said wall of said first tubing along said first longitudinal axis.
 7. The apparatus recited in claim 5 wherein said second ridge is arcuate in a second plane orthogonal to said direction of flow.
 8. The apparatus recited in claim 5 wherein said first tubing comprises a second outside diameter, said second ridge comprises a second width, and said second width is less than said second outside diameter.
 9. The apparatus recited in claim 3 wherein said first tubing comprises a transverse axis and said first ridge is centered with respect to said transverse axis; and, wherein said stop platen is arranged to be moved to a first position closest to said tubing base and where in said first position, said second ridge is centered with respect to said transverse axis.
 10. The apparatus recited in claim 9 wherein said first and second ridges are symmetrical with respect to said transverse axis.
 11. The apparatus recited in claim 3 wherein said first tubing comprises an inside wall with first and second segments; and, wherein said stop platen is arranged to be moved to a second position closest to said tubing base and where in said second position, said first and second segments are in contact and said first tubing is formed in first and second lobes, said lobes forming passages through said first tubing.
 12. The apparatus recited in claim 11 wherein said first and second lobes are symmetrical with respect to said first longitudinal axis.
 13. The apparatus recited in claim 1 further comprising a second tubing, said second tubing comprising a second longitudinal axis aligned with said direction of flow; and, said apparatus further comprising: a pump platen, said pump platen comprising a concavity parallel to said second longitudinal axis, said concavity arranged to hold said second tubing, and said concavity comprising said stop platen.
 14. A method for pumping fluid through tubing comprising: supporting a tubing on a tubing support surface; and, engaging a wall of said tubing with a first ridge on a stop platen, said engaging along a longitudinal axis of said tubing.
 15. The method recited in claim 14 wherein said tubing support surface further comprises a second ridge; and, said method further comprising: aligning said second ridge with said longitudinal axis.
 16. The apparatus recited in claim 15 wherein said first and second ridges are arcuate in a plane orthogonal to said longitudinal axis.
 17. The method recited in claim 15 wherein said tubing comprises an outside diameter, said first and second ridges comprise respective widths, and said respective widths are each less than said outside diameter.
 18. The method recited in claim 15 wherein said tubing comprises a transverse axis; and, said method further comprising: centering said first ridge with respect to said transverse axis; and, moving said stop platen to a position closest to said tubing base, where in said position, said second ridge is centered with respect to said transverse axis.
 19. The apparatus recited in claim 18 further comprising: holding said tubing in a concavity, said concavity parallel to said longitudinal axis; disposing said stop platen in said concavity; and, forming said tubing into first and second lobes.
 20. The method recited in claim 19 wherein said first and second lobes are symmetrical with respect to said longitudinal axis. 